Add fancy CLI options

PFERD/__main__.py

@@ -1,40 +1,229 @@
 import argparse
 import asyncio
+import configparser
 from pathlib import Path
 
 from .config import Config, ConfigDumpException, ConfigLoadException
+from .output_dir import OnConflict, Redownload
 from .pferd import Pferd
 
+GENERAL_PARSER = argparse.ArgumentParser(add_help=False)
+GENERAL_PARSER.add_argument(
+    "--config", "-c",
+    type=Path,
+    metavar="PATH",
+    help="custom config file"
+)
+GENERAL_PARSER.add_argument(
+    "--dump-config",
+    nargs="?",
+    const=True,
+    metavar="PATH",
+    help="dump current configuration to a file and exit."
+    " Uses default config file path if no path is specified"
+)
+GENERAL_PARSER.add_argument(
+    "--crawler",
+    action="append",
+    type=str,
+    metavar="NAME",
+    help="only execute a single crawler."
+    " Can be specified multiple times to execute multiple crawlers"
+)
+GENERAL_PARSER.add_argument(
+    "--working-dir",
+    type=Path,
+    metavar="PATH",
+    help="custom working directory"
+)
+
+
+def load_general(
+        args: argparse.Namespace,
+        parser: configparser.ConfigParser,
+) -> None:
+    section = parser[parser.default_section]
+
+    if args.working_dir is not None:
+        section["working_dir"] = str(args.working_dir)
+
+
+CRAWLER_PARSER = argparse.ArgumentParser(add_help=False)
+CRAWLER_PARSER_GROUP = CRAWLER_PARSER.add_argument_group(
+    title="general crawler arguments",
+    description="arguments common to all crawlers",
+)
+CRAWLER_PARSER_GROUP.add_argument(
+    "--redownload",
+    type=Redownload.from_string,
+    metavar="OPTION",
+    help="when to redownload a file that's already present locally"
+)
+CRAWLER_PARSER_GROUP.add_argument(
+    "--on-conflict",
+    type=OnConflict.from_string,
+    metavar="OPTION",
+    help="what to do when local and remote files or directories differ"
+)
+CRAWLER_PARSER_GROUP.add_argument(
+    "--transform", "-t",
+    action="append",
+    type=str,
+    metavar="RULE",
+    help="add a single transformation rule. Can be specified multiple times"
+)
+CRAWLER_PARSER_GROUP.add_argument(
+    "--max-concurrent-tasks",
+    type=int,
+    metavar="N",
+    help="maximum number of concurrent tasks (crawling, downloading)"
+)
+CRAWLER_PARSER_GROUP.add_argument(
+    "--max-concurrent-downloads",
+    type=int,
+    metavar="N",
+    help="maximum number of tasks that may download data at the same time"
+)
+CRAWLER_PARSER_GROUP.add_argument(
+    "--delay-between-tasks",
+    type=float,
+    metavar="SECONDS",
+    help="time the crawler should wait between subsequent tasks"
+)
+
+
+def load_crawler(
+        args: argparse.Namespace,
+        section: configparser.SectionProxy,
+) -> None:
+    if args.redownload is not None:
+        section["redownload"] = args.redownload.value
+    if args.on_conflict is not None:
+        section["on_conflict"] = args.on_conflict.value
+    if args.transform is not None:
+        section["transform"] = "\n" + "\n".join(args.transform)
+    if args.max_concurrent_tasks is not None:
+        section["max_concurrent_tasks"] = str(args.max_concurrent_tasks)
+    if args.max_concurrent_downloads is not None:
+        section["max_concurrent_downloads"] = str(args.max_concurrent_downloads)
+    if args.delay_between_tasks is not None:
+        section["delay_between_tasks"] = str(args.delay_between_tasks)
+
+
+PARSER = argparse.ArgumentParser(parents=[GENERAL_PARSER])
+PARSER.set_defaults(command=None)
+SUBPARSERS = PARSER.add_subparsers(title="crawlers")
+
+
+LOCAL_CRAWLER = SUBPARSERS.add_parser(
+    "local",
+    parents=[GENERAL_PARSER, CRAWLER_PARSER],
+)
+LOCAL_CRAWLER.set_defaults(command="local")
+LOCAL_CRAWLER_GROUP = LOCAL_CRAWLER.add_argument_group(
+    title="local crawler arguments",
+    description="arguments for the 'local' crawler",
+)
+LOCAL_CRAWLER_GROUP.add_argument(
+    "target",
+    type=Path,
+    metavar="TARGET",
+    help="directory to crawl"
+)
+LOCAL_CRAWLER_GROUP.add_argument(
+    "output",
+    type=Path,
+    metavar="OUTPUT",
+    help="output directory"
+)
+LOCAL_CRAWLER_GROUP.add_argument(
+    "--crawl-delay",
+    type=float,
+    metavar="SECONDS",
+    help="artificial delay to simulate for crawl requests"
+)
+LOCAL_CRAWLER_GROUP.add_argument(
+    "--download-delay",
+    type=float,
+    metavar="SECONDS",
+    help="artificial delay to simulate for download requests"
+)
+LOCAL_CRAWLER_GROUP.add_argument(
+    "--download-speed",
+    type=int,
+    metavar="BYTES_PER_SECOND",
+    help="download speed to simulate"
+)
+
+
+def load_local_crawler(
+        args: argparse.Namespace,
+        parser: configparser.ConfigParser,
+) -> None:
+    parser["crawl:local"] = {}
+    section = parser["crawl:local"]
+    load_crawler(args, section)
+
+    section["type"] = "local"
+    section["target"] = str(args.target)
+    section["output_dir"] = str(args.output)
+    if args.crawl_delay is not None:
+        section["crawl_delay"] = str(args.crawl_delay)
+    if args.download_delay is not None:
+        section["download_delay"] = str(args.download_delay)
+    if args.download_speed is not None:
+        section["download_speed"] = str(args.download_speed)
+
+
+def load_parser(
+        args: argparse.Namespace,
+) -> configparser.ConfigParser:
+    parser = configparser.ConfigParser()
+
+    if args.command is None:
+        Config.load_parser(parser, path=args.config)
+    elif args.command == "local":
+        load_local_crawler(args, parser)
+
+    load_general(args, parser)
+    prune_crawlers(args, parser)
+
+    return parser
+
+
+def prune_crawlers(
+        args: argparse.Namespace,
+        parser: configparser.ConfigParser,
+) -> None:
+    if not args.crawler:
+        return
+
+    for section in parser.sections():
+        if section.startswith("crawl:"):
+            # TODO Use removeprefix() when switching to 3.9
+            name = section[len("crawl:"):]
+            if name not in args.crawler:
+                parser.remove_section(section)
+
+    # TODO Check if crawlers actually exist
+
 
 def main() -> None:
-    parser = argparse.ArgumentParser()
-    parser.add_argument(
-        "--config", "-c",
-        type=Path,
-        metavar="PATH",
-        help="specify custom config file path",
-    )
-    parser.add_argument(
-        "--dump-config",
-        nargs="?",
-        const=True,
-        type=Path,
-        metavar="PATH",
-        help="dump current configuration to a file and exit."
-        " Uses default config file path if no path is specified",
-    )
-    args = parser.parse_args()
+    args = PARSER.parse_args()
 
     try:
-        config_parser = Config.load_parser(args.config)
-        config = Config(config_parser)
+        config = Config(load_parser(args))
     except ConfigLoadException:
         exit(1)
 
-    if args.dump_config:
-        path = None if args.dump_config is True else args.dump_config
+    if args.dump_config is not None:
         try:
-            config.dump(path)
+            if args.dump_config is True:
+                config.dump()
+            elif args.dump_config == "-":
+                config.dump_to_stdout()
+            else:
+                config.dump(Path(args.dump_config))
         except ConfigDumpException:
             exit(1)
         exit()

PFERD/config.py

@@ -1,4 +1,6 @@
+import asyncio
 import os
+import sys
 from configparser import ConfigParser, SectionProxy
 from dataclasses import dataclass
 from pathlib import Path
@@ -68,7 +70,7 @@ class Config:
         raise ConfigLoadException()
 
     @staticmethod
-    def load_parser(path: Optional[Path] = None) -> ConfigParser:
+    def load_parser(parser: ConfigParser, path: Optional[Path] = None) -> None:
         """
         May throw a ConfigLoadException.
         """
@@ -76,8 +78,6 @@ class Config:
         if not path:
             path = Config._default_path()
 
-        parser = ConfigParser()
-
         # Using config.read_file instead of config.read because config.read
         # would just ignore a missing file and carry on.
         try:
@@ -90,8 +90,6 @@ class Config:
         except PermissionError:
             Config._fail_load(path, "Insufficient permissions")
 
-        return parser
-
     @staticmethod
     def _fail_dump(path: Path, reason: str) -> None:
         print(f"Failed to dump config file to {path}")
@@ -123,7 +121,7 @@ class Config:
                     self._parser.write(f)
             except FileExistsError:
                 print("That file already exists.")
-                if prompt_yes_no("Overwrite it?", default=False):
+                if asyncio.run(prompt_yes_no("Overwrite it?", default=False)):
                     with open(path, "w") as f:
                         self._parser.write(f)
                 else:
@@ -133,6 +131,9 @@ class Config:
         except PermissionError:
             self._fail_dump(path, "Insufficient permissions")
 
+    def dump_to_stdout(self) -> None:
+        self._parser.write(sys.stdout)
+
     @property
     def default_section(self) -> SectionProxy:
         return self._parser[self._parser.default_section]

PFERD/crawler.py

@@ -117,37 +117,25 @@ class CrawlerSection(Section):
 
     def redownload(self) -> Redownload:
         value = self.s.get("redownload", "never-smart")
-        if value == "never":
-            return Redownload.NEVER
-        elif value == "never-smart":
-            return Redownload.NEVER_SMART
-        elif value == "always":
-            return Redownload.ALWAYS
-        elif value == "always-smart":
-            return Redownload.ALWAYS_SMART
-
-        self.invalid_value(
-            "redownload",
-            value,
-            "Must be 'never', 'never-smart', 'always' or 'always-smart'"
-        )
+        try:
+            return Redownload.from_string(value)
+        except ValueError as e:
+            self.invalid_value(
+                "redownload",
+                value,
+                str(e).capitalize(),
+            )
 
     def on_conflict(self) -> OnConflict:
         value = self.s.get("on_conflict", "prompt")
-        if value == "prompt":
-            return OnConflict.PROMPT
-        elif value == "local-first":
-            return OnConflict.LOCAL_FIRST
-        elif value == "remote-first":
-            return OnConflict.REMOTE_FIRST
-        elif value == "no-delete":
-            return OnConflict.NO_DELETE
-
-        self.invalid_value(
-            "on_conflict",
-            value,
-            "Must be 'prompt', 'local-first', 'remote-first' or 'no-delete'",
-        )
+        try:
+            return OnConflict.from_string(value)
+        except ValueError as e:
+            self.invalid_value(
+                "on_conflict",
+                value,
+                str(e).capitalize(),
+            )
 
     def transform(self) -> str:
         return self.s.get("transform", "")

PFERD/output_dir.py

@@ -32,6 +32,14 @@ class Redownload(Enum):
     ALWAYS = "always"
     ALWAYS_SMART = "always-smart"
 
+    @staticmethod
+    def from_string(string: str) -> "Redownload":
+        try:
+            return Redownload(string)
+        except ValueError:
+            raise ValueError("must be one of 'never', 'never-smart',"
+                             " 'always', 'always-smart'")
+
 
 class OnConflict(Enum):
     PROMPT = "prompt"
@@ -39,6 +47,14 @@ class OnConflict(Enum):
     REMOTE_FIRST = "remote-first"
     NO_DELETE = "no-delete"
 
+    @staticmethod
+    def from_string(string: str) -> "OnConflict":
+        try:
+            return OnConflict(string)
+        except ValueError:
+            raise ValueError("must be one of 'prompt', 'local-first',"
+                             " 'remote-first', 'no-delete'")
+
 
 @dataclass
 class Heuristics: